NiAl layered double hydroxides with enhanced interlayer spacing via ion-exchange as ultra-high performance supercapacitors electrode materials

Supercapacitors play a significant role in energy storage systems, and much efforts have been devoted to the development of electrode materials with excellent electrochemical properties. Here, a flower-like spherical NiAl layered double hydroxide with chloride ions as interlayer anions (NiAl-Cl LDH) is successfully prepared via a two-step method, which exhibits a prominent specific capacity of 2512 F/g (379.7 mAh/g) at a current density of 1 A/g is much higher than that of the precursor. NiAl-Cl LDH presents widen interlayer spacing that can promote transport kinetics of OH− ion and electrons between the brucite-like layers and improve the utilization of active materials, resulting in superior rate capability (the specific capacitance at 20 A/g is 77.5% of that at 1A/g). Meanwhile, the interspace between the interlaced hierarchical structure is beneficial to buffer the volume change, ensuring the structural stability of NiAl-Cl LDH during the redox reaction. Furthermore, the assembled NiAl-Cl LDH//AC asymmetric supercapacitor exhibits a high energy density of 53.9 Wh/kg corresponding to a power density of 1540 W/kg, and remains 94.1% of initial specific capacitance after 1000 cycles examinations.